Landing gear for aircraft



June 20, 1939. A. P. DE SEVERSKY LANDING GEAR FOR AIRCRAFT Original Filed April 25, l9 28 3 Sheets-Sheet l ALEXANDER R as Sevensnv June 20, 1939. A. P. DE SEVERSKY Re. 21,120

LANDING GEAR FOR AIRCRAFT 3 Sheets-Sheet 2 Original Filed April 25, 1928 awuwntoz Ausxmam P as SEVERJK'.

%% flame/1 'June 20, 1939. A. P. DE SEVERSKY 21,120

LANDING GEAR FOR AIRCRAFT I Original Filed'April 25, 1928 3 Sheets-Sheet 3 anveutoz ALEXANDER Fae SzvzksnY Reissued June 20, 1939 UNITED STATES! PATENT OFFICE signor, by mesne assignments, to Seversky Aircraft Corporation, a corporation of Delaware Original No. 2,007,752, dated July 9, 1935, Serial No. 272,627, April 25, 1928. Renewed August 10, 1932. Application for reissue July 9, 1937, a

Serial No. 152,865

9 Claims. (01. 244- 1o1) The present invention relates to aircraft and has for an object to provide an improved amphibian landing gear.

k The invention provides a landing gear having .in the preferred embodiment, a plurality of pone toons each connected resiliently to the craft and each carrying a wheel arranged to engage the ground to take the load when landing on the ground. The arrangement of the preferred embodiment to be herein more particularly described is such that the pontoons for landing on the water or the wheels for landing on the ground are immediately available for landing or taking ofl without any manual adjustment of eithe I The nature and objects of the invention will be better understood from a description of a selective embodiment for the purpose of which description reference should be had to the accompanying drawings forming a part hereof and in which- Figure 1 is a view in side elevation of an aircraft embodying the invention,

Figure2 is a similar view but showing the parts in position assumed when landing,

Figure 3 is a top plan view of the same,

Figure 4 is-a view in front elevation,

Figure 5 is a sectional detail view taken on the line 5-5 of Fig. 1, l

Figure 6 is a sectional view taken on the line 6-5 of Fig. 7,

Figure 7 is a horizontal sectional view taken on the line of Fig. 6, and

Figure 8' is a view in front elevation of the center portion of the under frame of the landing gear.

Referring to the embodiment shown for the purpose of illustrating the principles of the invention, an aircraft fuselage 5 carries a landing gear having an underframe i supporting a pair of pontoons l with'wheels 8, a third pontoon, or-

float, 9 being carried by the rear end of the fuse lage to support the tail of the craft. The framework 5 comprises substantially horizontal axle members In, to the outer ends of which the ponlage. It is desirable that the pontoons be permitted a rocking movement about the axle members to which they are pivotally supported, while at the same time it is important to prevent lateral turning thereof. In the construction shown, the pontoons are pivoted to the underframe at I5 for rocking movement in a longitudinal plane but lateral movement about a vertical axis or lateral movement about a longitudinal horizontal axis is prevented by means of braces |G fitted rigidly to the pontoons toward the forward and rear ends thereof and the coupling members These braces H; are so designed that stresses tending to turn the pontoons about a vertical axis will be.

tween the braces l6, and the coupling may inelude at each .side a sleeve l8 having trunnions l9 engaged by the braces.

As shown, each pontoon is connected to the underframe by means including a shock absorber mechanism housed within the pontoon and arranged to permit a limited resilience in landing. In the structure shown a dashpot 20 serves as a cushioning device between the underframe and the pontoon. A central plunger 2| is pivoted to the underframe and operates 'in a cylinder 22 forming a rigid part of the pontoon. The plunger 2| is hollow and has a restricted opening 23 in the lower end thereof to permit restricted flow of.

oil from the cylinder 22 into the hollow of the plunger thus to yieldably support the load of the plane when landing. The connection between the plunger 2| and the underframe provides for a limited relative lateral movement to avoid binding, as indicated at 24. buffer rings 25 are provided around the plunger 2| in position to be engaged by a collar 28 on said plunger as the plunger approaches its lowermost position in the cylinder 22. During flight the pontoon will move by its own weight to lowermost position relative to the plunger 2| thus automatically taking the desired position for llanding.

In order that the landing gear mayoperate effectively when landing on or taking off from the ground the pontoons are provided with the wheels 8 rotatably mounted in the pontoons a relatively short distance in front of the point of pivotal support of the pontoons on the under- A number of rubber wheels 8 and skids 30 formed at the rear of the pontoons. When the tail of the craft is down, its weight is supported on a skid 32 which conveniently may project from the pontoon 9 on the tail of the fuselage.

By the arrangement described, it is possible to land alternatively upon the water or on the ground without making any adjustment of the landing gear and yet an effective .three'point landing can be made in either event. The position of the pontoon and tail skid 32 when making a three point landing is indicated in Fig. 2 where the ground level is indicated by the line 34 and the water line by a line. The pontoon is self stabilizing.

Figs. 6 and '7 show another form of shock absorbing device which may be connected between the underframe and the pontoon in any suitable way. This device comprises a plunger member 31 operating within a piston 38 and having an exterior casing 39'arranged to enclose the cylinder 38. The lower end of the plunger is provided with a restricted aperture II) in order that the air or oil within the cylinder and plunger may provide a cushioning effect. A spring II in the cylinder 38 engages the end of the plunger 31 and resists inward movement thereof. Shock absorbing buil'er rings 43 of rubber or other suitable material are provided to reduce the shock at the limit of the downward movement of the pontoon and similar buffer rings 44 similarly resist the shock at the end of the upward movement of the pontoon during landing. If the device projects above the pontoon a streamlineshell 45 is preferabl'y provided.

The foregoing description is illustrative merely and is not intended as defining the limits of the invention.

I claim:

1. An aircraft comprising, in combination, a fuselage, a support dependent therefrom, a pontoon pivoted to said support, a wheel rotatably mounted in said pontoon forward of the pivotal support thereof, a skid at the rear end of said pontoon arranged to cooperate with said wheel to support said pontoon on the ground, an independent skid at the rear of said fuselage rearwardly of said pontoon, substantially as described.

2. An aircraft, as defined in claim 1, wherein a shock absorbing mechanism is arranged between the pontoon and the support thereof, substantially as described.

3. An aircraft, as defined in claim 1, having a pontoon at the rear end of the fuselage, substantially as described.

4. An aircraft comprising a fuselage, a pair of pontoons and a tail float connected to the fuselage, said pontoons being provided with wheels and said pontoons and float being provided with skids at the rear end of each, whereby a three point landing may be made upon the ground or in the water, substantially as described.

5. A shock absorber for aircraft landing gear comprising a member providing a central plunger and an outer cylinder casing, a movable cylinder enclosing said plunger and having a head engaging said cylinder casing and rubber buffer rings between said head and opposite ends of said member for resisting shocks at the extreme limit of movement in both directions, substantially as described.

6. A shock absorber for aircraft landing gear comprising a plunger, a movable cylinder enclosing said plunger, said plunger having a head movable for a considerable distance in said cylinder to resiliently resist shocks and rubber buffer rings on both sides of said head for resisting shocks at the extreme limit of movement in both directions, substantially as described. I

7. An aircraft landing gear comprising an underframe including a cabane, a pair of pontoons at opposite sides of said cabane a shock absorber connecting each pontoon to the cabane and forming the principal support between the frame and the pontoon and by which the pontoon is supported for vertical and rocking movement in a longitudinal vertical plane, braces extending diagonally outward from the cabane fore and aft to the pontoons and rigidly secured thereto, said braces preventing movement of the pontoon from its longitudinal vertical plane while permitting rocking and vertical movement in said plane.

8. An aircraft comprising a fuselage, a supporting frame depending therefrom and having a central member II and transverse members I0 extending laterally therefrom, a pair of pontoons, shock absorbers between the outer ends of'the transverse members and the pontoons by which the pontoons are supported for vertical and pivotal movement in longitudinal vertical planes, and braces l6 extending from the center member ll diagonally outward and respectively fore and aft, said braces being rigidly connected to the pontoons and inhibiting movement thereof out of the longitudinal vertical plane.

9. An aircraft comprising, in combination, a fuselage, a rigid support dependent therefrom and extending below the fuselage, a pontoon piv- 1 oted to said support, awheel rotatably mounted in said pontoon forward of the pivotal support thereof, a landing surface engaging means at the rear end of said pontoon arranged to cooperate with said wheel to support said pontoon on the landing surface, and independent, land and water landing surface engaging means at the rear of said fuselage.

-ALEXANDER P. DE SEVERSKY. 

